--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api.dsl.test/src/com/oracle/truffle/api/dsl/test/SourceSectionTest.java	Mon Aug 25 15:56:32 2014 +0200
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.truffle.api.dsl.test;
+
+import static com.oracle.truffle.api.dsl.test.TestHelper.*;
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+
+import org.junit.experimental.theories.*;
+import org.junit.runner.*;
+
+import com.oracle.truffle.api.dsl.*;
+import com.oracle.truffle.api.dsl.test.SourceSectionTestFactory.SourceSection0Factory;
+import com.oracle.truffle.api.dsl.test.TypeSystemTest.*;
+import com.oracle.truffle.api.nodes.*;
+import com.oracle.truffle.api.source.*;
+
+@RunWith(Theories.class)
+public class SourceSectionTest {
+
+    @DataPoints public static final int[] data = new int[]{1, 2, 3, 4};
+
+    @Theory
+    public void testSourceSections(int value0, int value1, int value2) {
+        TestRootNode<SourceSection0> root = createRoot(SourceSection0Factory.getInstance());
+        SourceSection section = new NullSourceSection("a", "b");
+        root.getNode().assignSourceSection(section);
+        expectSourceSection(root.getNode(), section);
+        assertThat((int) executeWith(root, value0), is(value0));
+        expectSourceSection(root.getNode(), section);
+        assertThat((int) executeWith(root, value1), is(value1));
+        expectSourceSection(root.getNode(), section);
+        assertThat((int) executeWith(root, value2), is(value2));
+        expectSourceSection(root.getNode(), section);
+    }
+
+    private void expectSourceSection(Node root, SourceSection section) {
+        assertThat(root.getSourceSection(), is(sameInstance(section)));
+        for (Node child : root.getChildren()) {
+            if (child instanceof ArgumentNode) {
+                continue;
+            }
+            if (child != null) {
+                expectSourceSection(child, section);
+            }
+        }
+    }
+
+    @NodeChild("a")
+    static class SourceSection0 extends ValueNode {
+
+        boolean isOne(int a) {
+            return a == 1;
+        }
+
+        boolean isTwo(int a) {
+            return a == 2;
+        }
+
+        boolean isThree(int a) {
+            return a == 3;
+        }
+
+        @Specialization(guards = "isOne")
+        int do1(int a) {
+            return a;
+        }
+
+        @Specialization(guards = "isTwo")
+        int do2(int a) {
+            return a;
+        }
+
+        @Specialization(guards = "isThree")
+        int do3(int a) {
+            return a;
+        }
+
+        @Fallback
+        Object do4(Object a) {
+            return a; // the generic answer to all questions
+        }
+    }
+}

--- a/graal/com.oracle.truffle.api.dsl/src/com/oracle/truffle/api/dsl/internal/DSLShare.java	Mon Aug 25 14:43:43 2014 +0200
+++ b/graal/com.oracle.truffle.api.dsl/src/com/oracle/truffle/api/dsl/internal/DSLShare.java	Mon Aug 25 15:56:32 2014 +0200
@@ -96,29 +96,39 @@
         }
     }
 
-    public static <T extends Node & DSLNode> T rewriteToPolymorphic(Node oldNode, DSLNode uninitialized, T polymorphic, DSLNode currentCopy, DSLNode newNode, String message) {
+    public static <T extends Node & DSLNode> T rewriteToPolymorphic(Node oldNode, DSLNode uninitializedDSL, T polymorphic, DSLNode currentCopy, DSLNode newNodeDSL, String message) {
         assert getNext(oldNode) == null;
         assert getPrevious(oldNode) == null;
 
+        Node uninitialized = (Node) uninitializedDSL;
+        Node newNode = (Node) newNodeDSL;
         polymorphic.adoptChildren0(oldNode, (Node) currentCopy);
 
+        updateSourceSection(oldNode, uninitialized);
         if (newNode == null) {
             // fallback
-            currentCopy.adoptChildren0(null, (Node) uninitialized);
+            currentCopy.adoptChildren0(null, uninitialized);
         } else {
             // new specialization
-            newNode.adoptChildren0(null, (Node) uninitialized);
-            currentCopy.adoptChildren0(null, (Node) newNode);
+            updateSourceSection(oldNode, newNode);
+            newNodeDSL.adoptChildren0(null, uninitialized);
+            currentCopy.adoptChildren0(null, newNode);
         }
 
         oldNode.replace(polymorphic, message);
 
         assert polymorphic.getNext0() == currentCopy;
         assert newNode != null ? currentCopy.getNext0() == newNode : currentCopy.getNext0() == uninitialized;
-        assert uninitialized.getNext0() == null;
+        assert uninitializedDSL.getNext0() == null;
         return polymorphic;
     }
 
+    private static void updateSourceSection(Node oldNode, Node newNode) {
+        if (newNode.getSourceSection() == null) {
+            newNode.assignSourceSection(oldNode.getSourceSection());
+        }
+    }
+
     private static Class<?>[] mergeTypes(DSLNode node, Class<?>[] types) {
         Class<?>[] specializedTypes = node.getMetadata0().getSpecializedTypes();
         if (specializedTypes.length == 0) {
@@ -154,6 +164,7 @@
         }
         assert prev.getCost() == NodeCost.POLYMORPHIC;
 
+        updateSourceSection(prev, newNode);
         if (depth == 0) {
             newNode.adoptChildren0(prev, null);
             return prev.replace(newNode, "Polymorphic to monomorphic.");